Actually, for a short period of time(2-3 months) I went on the Uberman Sleep Schedule. This was during the summer (I'm still in school), so I had nothing better to do.
Now, in the actual mechanics of how I got around to doing this: Instead of starting out conforming to the 20/30 min naps, I just started taking lots of naps. I started with one about halfway through my day, and it went on like that. The number of naps increased, while the amount of time each took went down. Eventually, I evened out at 6 naps of 30 min each (the instructions I had gotten were slightly different), meaning three hours of sleep per 24 hour day.
Now, to repeat the warning: Do not, under any circumstances, delay a nap by more than an hour. I was able to strech around a bit, but when I missed a nap, it was horrible.
Another thing about this, is that I've heard of your body not getting some of the chemicals it needs. Your body generates various chemicals in the third and fourth stage sleep that you don't get while on the Uberman. Eating grapes helps, as they contain most of the chemicals you need. You might get some weird cravings, and you should generally listen to your body. This is not a very healthy way of sleeping, but you can balance it out with other things.